As a so-called super-resolution technology to enhance the resolution of photographed images, a variety of technologies that combine a plurality of photographed images to enhance the resolution of the images have been proposed heretofore (see, e.g., Patent Literatures (hereinafter, abbreviated as “PTL”) 1 and 2).
FIG. 1 shows an image obtained by a super-resolution technology using a plurality of photographed images. As depicted in the figure, a super-resolution image is formed by synthesizing a plurality of (N) low-resolution images. Specifically, alignment with sub-pixel (smaller than one-pixel size) accuracy is performed first on a plurality of low-resolution images of the same subject photographed using a camera. Then, the plurality of images after the alignment are synthesized. As a result, the resolution of the synthesized image (super-resolution image) is enhanced because the number of spatial sample points increases and the sampling frequency increases accordingly.